Question: What significant event for Buzz Aldrin began on July 21, 1969?
Paraphrase: What important task did Buzz Aldrin begin on July 21, 1969?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q2252 p:P793 ?s . ?s ps:P793 ?obj . ?s pq:P580 ?x filter(contains(YEAR(?x),'1969')) }